WO2021000336A1 - Battery module - Google Patents

Abstract

The present application relates to a battery module, comprising: two or more battery units, wherein each of the battery units comprises a battery cell, the battery cell is provided with two end portions opposite each other in the length direction of the battery cell, and the two or more battery units are arranged side by side in the thickness direction of the battery cell; and in two adjacent battery units, a first gap is formed between two battery cells close to each other, and the first gap extends from an end portion in the length direction, with in a direction from the end portion to the center of the battery cell, the size of the first gap being gradually reduced in the thickness direction. The battery module further comprises: a cushion pad, wherein the cushion pad is arranged between the two adjacent battery units, and the cushion pad is arranged in the first gap and is in contact with the end portions of the battery cell. According to the battery module in the embodiments of the present application, a gap between a first pole piece and a second pole piece can be effectively reduced by means of a cushion pad, and the possibility of a lithium precipitation phenomenon occurring at an end portion of a battery cell is reduced, thereby improving the whole cycle performance of the battery module.

Description

Battery module

Cross references to related applications

This application claims the priority of the Chinese patent application 201921040744.0 named "Battery Module" filed on July 4, 2019, the entire content of which is incorporated herein by reference.

Technical field

This application relates to the field of battery technology, and in particular to a battery module.

Background technique

With the development and progress of science and technology, the application range of secondary batteries is becoming wider and wider. For example, secondary batteries can be applied to electric vehicles, energy storage and other fields. The battery module includes a casing and a plurality of battery cells arranged in the casing. Each battery cell includes a battery cell. The cell includes an electrode assembly and a packaging bag covering the electrode assembly. The battery core has two opposite ends. The electrode assembly has a first pole piece and a second pole piece with opposite polarities. The electrode assembly may be formed by stacking the first pole piece, the second pole piece, and the separator together or spirally winding around the winding axis. After the first pole piece and the second pole piece are cold-pressed, the thickness of the first pole piece and the second pole piece near the edge is smaller than the thickness of the central area. Therefore, the gap between the first pole piece and the second pole piece of the electrode assembly at the end of the cell will become larger and larger than the gap between the first pole piece and the second pole piece in the center area of the cell, so that it is easy to Lithium evolution occurs at the end of the cell, which affects the cycle performance of the cell.

Summary of the invention

The embodiments of the present application provide a battery module, which can effectively reduce the gap between the first pole piece and the second pole piece through a buffer pad, reduce the possibility of lithium evolution at the end of the battery cell, and improve the improvement The overall cycle performance of the battery module.

On the one hand, an embodiment of the present application proposes a battery module, which includes:

Two or more battery cells, the battery cell includes a battery cell, the battery cell has two opposite ends along its own length direction, two or more battery cells are arranged side by side along the thickness direction of the battery cell, in two adjacent battery cells, A first gap is formed between the two cells that are close to each other. The first gap extends from one end in the length direction, and from the end to the center of the cell, the size of the first gap in the thickness direction is gradually reduced. Small; buffer pad; wherein a buffer pad is arranged between two adjacent battery cells, the buffer pad is arranged in the first gap and is in contact with the end of the battery cell.

According to one aspect of the embodiments of the present application, along the length direction, the first gap is penetrated, and the buffer pad includes a first buffer portion and a second buffer portion; along the thickness direction, one of the two ends of the battery is One buffer part is arranged in an arrangement, and the other end part is arranged in an arrangement with the second buffer part.

According to one aspect of the embodiments of the present application, the cushion pad further includes an intermediate portion, which is disposed between the first cushion portion and the second cushion portion and is in contact with the battery core.

According to an aspect of the embodiments of the present application, the surfaces of the first buffer portion, the second buffer portion, and the middle portion facing the battery core are connected to each other and transition smoothly, and/or the surface of the battery core forming the first gap is an arched surface, The surfaces of the first buffer portion, the second buffer portion and the middle portion facing the battery core are attached to the battery core.

According to one aspect of the embodiments of the present application, the first buffer part, the second buffer part and the intermediate part are an integrated structure.

According to one aspect of the embodiment of the present application, along the length direction, the end surface of the first buffer portion is aligned with the end surface of the battery cell, and/or, along the length direction, the end surface of the second buffer portion is aligned with the end surface of the battery core.

According to one aspect of the embodiments of the present application, along the length direction, the ratio of the size of the first buffer portion to the size of the battery core is 0.06 to 0.15, and/or the ratio of the size of the second buffer portion to the size of the battery core is 0.06 To 0.15;

Or, along the width direction of the battery core, the size of the buffer pad and the battery core are equal.

According to one aspect of the embodiments of the present application, the battery cell includes an electrode assembly and a packaging bag, the electrode assembly is arranged in the packaging bag, and the electrode assembly includes a first pole piece and a second pole piece with opposite polarities, from the end to the battery core In the direction of the center, the thickness of the first pole piece and the second pole piece gradually increase.

According to one aspect of the embodiments of the present application, the battery module further includes a casing, the battery unit is arranged in the casing, and a second gap is formed between the battery cell near the casing and the casing, and the distance from the end to the center of the battery cell In the direction, the size of the second gap along the thickness direction is gradually reduced, and a buffer pad is arranged in the second gap, and the buffer pad is in contact with the end of the battery core.

According to one aspect of the embodiments of the present application, the battery unit includes more than two battery cells, and a rigid isolation component is arranged between two adjacent battery cells.

The battery module according to the embodiment of the present application includes more than two battery units and a buffer pad arranged between two adjacent battery units. Along the thickness direction, the buffer pad is arranged between the two battery cells. In two adjacent battery cells, a first gap is formed between two adjacent battery cells. The buffer pad is arranged in the first gap and is in contact with the end of the battery core. The buffer pad provides support stress for the end of the battery cell, which can effectively reduce the gap between the first pole piece and the second pole piece, reduce the possibility of lithium evolution at the end of the battery cell, and improve the battery The overall cycle performance of the module.

Description of the drawings

The features, advantages, and technical effects of exemplary embodiments of the present application will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of the overall structure of a battery module according to an embodiment of the present application;

Figure 2 is a schematic side view of the overall structure of a battery module according to an embodiment of the present application;

Figure 3 is a schematic sectional view of the structure at A-A in Figure 2;

4 is a schematic side view of the structure of a battery core according to an embodiment of the present application;

FIG. 5 is a schematic diagram of an axonometric structure of a battery core according to an embodiment of the present application;

6 is a schematic cross-sectional view of the structure of the first pole piece according to an embodiment of the present application;

7 is a schematic cross-sectional view of the structure of a second pole piece according to an embodiment of the present application;

8 is a schematic cross-sectional view of a partially laminated structure of the first pole piece, the diaphragm, and the second pole piece included in the battery cell of an embodiment of the present application;

9 is a partial schematic diagram of the distribution of battery cells in a battery module according to an embodiment of the present application;

FIG. 10 is a schematic structural diagram of a buffer pad provided between battery cells in a battery module of an embodiment of the present application;

11 is a schematic diagram of the relationship between the number of battery cycles and the capacity retention rate of an embodiment of the present application;

FIG. 12 is a schematic diagram of the relationship between the number of battery cycles and the expansion force of an embodiment of the present application;

FIG. 13 is a schematic structural diagram of a buffer pad disposed between battery cells in a battery module according to another embodiment of the present application;

14 is a schematic structural diagram of a buffer pad disposed between battery cells in a battery module according to another embodiment of the present application;

15 is a partial schematic diagram of battery cell distribution in a battery module according to another embodiment of the present application;

FIG. 16 is a schematic structural diagram of a buffer pad provided between battery cells in a battery module according to another embodiment of the present application;

FIG. 17 is a schematic structural diagram of a buffer pad disposed between battery cells in a battery module according to another embodiment of the present application;

18 is a partial schematic diagram of battery cell distribution in a battery module according to another embodiment of the present application;

FIG. 19 is a schematic diagram of a structure in which a buffer pad is arranged between battery cells in a battery module according to another embodiment of the present application.

In the drawings, the drawings may not be drawn to actual scale.

Mark description:

10. Battery module;

20. Shell;

30. Battery cell; 31. Cell; 31a, end; 31b, end face; 32, first gap; 33, second gap; 34, electrode assembly; 34a, first pole piece; 34aa, first current collector; 34ab, the first active material layer; 34b, the diaphragm; 34c, the second pole piece; 34ca, the second current collector; 34cb, the second active material layer; 35, the packaging bag;

40. Cushion pad; 41. First buffer part; 42, second buffer part; 43. Middle part;

50. Rigid isolation parts;

X, length direction; Y, thickness direction; Z, width direction.

Detailed ways

The implementation of the present application will be described in further detail below in conjunction with the drawings and embodiments. The detailed description and drawings of the following embodiments are used to exemplarily illustrate the principles of the application, but cannot be used to limit the scope of the application, that is, the application is not limited to the described embodiments.

In the description of this application, it should be noted that, unless otherwise specified, "plurality" means two or more; the terms "upper", "lower", "left", "right", "inner", and " The orientation or positional relationship indicated by “outside” is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a reference to the present application. Application restrictions. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

In the description of this application, it should be noted that the terms "installation", "connection", and "connection" should be understood in a broad sense unless otherwise clearly specified and limited. For example, they may be fixed connections or alternatively. Disassembly connection, or integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above-mentioned terms in this application can be understood according to the specific circumstances.

In order to better understand the present application, the following describes the embodiments of the present application in conjunction with FIG. 1 to FIG. 19.

As shown in FIGS. 1 to 3, the battery module 10 of the embodiment of the present application includes a casing 20, two or more battery cells 30 arranged in the casing 20 and a buffer pad 40.

The housing 20 has an accommodation space in which the battery unit 30 is accommodated. The casing 20 can protect the battery unit 30. The battery unit 30 includes a battery cell 31 and a fixed frame (not shown in the figure). The battery core 31 is connected to the fixed frame. The fixing frame is beneficial to improve the overall structural strength of the battery module 10.

Referring to FIG. 4 and FIG. 5, the battery core 31 of this embodiment is a flat structure as a whole, which has a predetermined thickness, length, and width. The cell 31 has two ends 31a facing each other along the length direction X of the cell. Each end 31a has an end surface 31b. The end portion 31a of the battery core 31 is thinner and flatter than the central area of the battery core 31. The cell 31 includes an electrode assembly 34 and a packaging bag 35. The packaging bag 35 has an accommodation space, and the main body of the electrode assembly 34 is accommodated in the packaging bag 35. The packaging bag 35 may be a soft shell. Optionally, the packaging bag 35 can be made of aluminum plastic film or steel plastic film. The electrode assembly of this embodiment can be formed by stacking the first pole piece, the second pole piece, and the diaphragm together or spirally winding around the winding axis, wherein the diaphragm is between the first pole piece and the second pole piece. Between the insulators. In this embodiment, the first pole piece is used as a positive electrode piece and the second pole piece is a negative electrode piece for illustration. Similarly, in other embodiments, the first pole piece may also be a negative pole piece, and the second pole piece is a positive pole piece. In addition, the positive sheet active material is coated on the coating area of the positive sheet, and the negative sheet active material is coated on the coating area of the negative sheet. The uncoated area extending from the coated area of the main body is used as the tab. The electrode assembly includes two tabs, namely the positive tab and the negative tab. The positive tab extends from the coating area of the positive tab, and the negative tab extends from the negative tab. The coating area extends out.

6 and 7, the first pole piece 34a includes a first current collector 34aa and a first active material layer 34ab. The second pole piece 34c includes a second current collector 34ca and a second active material layer 34cb. Since the first pole piece 34a and the second pole piece 34c need to be cold pressed during the processing, the thickness of the first pole piece 34a and the second pole piece 34c after cold pressing is from the end 31a of the cell 31 to the electric The core 31 gradually increases in the direction of the center, so that the electrode assembly 34 formed by stacking or winding together the first pole piece 34a, the second pole piece 34c, and the diaphragm 34b of this embodiment has a thickness at both ends less than the center thickness. In turn, the overall battery core 31 also has a structure with a thickness at both ends less than the center thickness (see FIG. 4). As shown in FIG. 8, after the first pole piece 34a and the second pole piece 34c form the electrode assembly 34, the gap between the first pole piece 34a and the second pole piece 34c at the end 31a of the cell 31 will become larger. It is also larger than the gap between the first pole piece 34a and the second pole piece 34c in the central area of the cell 31.

Two or more battery cells 30 are arranged side by side along the thickness direction Y of the battery core 31. Among two adjacent battery units 30, the battery cell 31 of one battery unit 30 and the battery cell 31 of the other battery unit 30 are close to each other and are arranged opposite to each other. A first gap 32 is formed between the two cells 31 that are close to each other. The first gap 32 extends along the length direction X from one end portion 31a. From the end 31a of the cell 31 to the center of the cell 31, the size of the first gap 32 in the thickness direction Y gradually decreases, that is, from the end 31a of the cell 31 to the center of the cell 31, The size of a gap 32 in the thickness direction Y is changed from width to narrower. A buffer pad 40 is provided between two adjacent battery cells 30. The buffer pad 40 is disposed in the first gap 32 and is in contact with the end 31 a of the battery core 31. The end 31 a of the battery cell 31 is at least partially covered by the cushion 40. Along the thickness direction Y, the cell 31 has two wide surfaces. Along the width direction Z, the cell 31 has two narrow faces. Among the two adjacent battery cells 31, the wide surface of one battery core 31 is arranged corresponding to the wide surface of the other battery core 31. The area where the wide surface of the cell 31 forms the first gap 32 is curved. The cushion 40 has elasticity. Optionally, the material of the cushion pad 40 may be a material with cushioning properties such as silica gel or polyurethane.

The battery module 10 of the embodiment of the present application includes more than two battery cells 30 and a buffer pad 40 arranged between two adjacent battery cells 30. Along the thickness direction Y, the cushion pad 40 is disposed between the two battery cells 30. In two adjacent battery cells 30, a first gap 32 is formed between two battery cells 31 close to each other. The buffer pad 40 is disposed in the first gap 32 and is in contact with the end 31 a of the battery core 31. The buffer pad 40 can provide supporting stress for the end 31a of the cell 31, thereby effectively reducing the gap between the first pole piece 34a and the second pole piece 34c at the end 31a of the cell 31, reducing the The possibility of lithium evolution at the end 31a of 31 is improved to improve the overall cycle performance of the battery module 10.

In addition, during the cycle of the battery cell 31, the entire battery cell 31 may expand, and the end portion 31a of the battery cell 31 expands and exerts a pressing force on the cushion pad 40. When the buffer pad 40 is co-squeezed and compressed by the cells 31 on both sides, the buffer pad 40 can exert a reaction force on the cells 31 to prevent the end 31a of the cells 31 from expanding to a large extent, thereby helping to ensure the power The degree of expansion of the end portion 31a of the core 31 and the degree of expansion of the central area of the cell 31 tend to coincide. In this way, the buffer pad 40 is added between the battery cells 30, which can effectively restrain the expansion of the end 31a, which is beneficial to reduce the possibility of lithium evolution caused by the excessive expansion of the end 31a, and reduce the possibility of the occurrence of lithium evolution. The possibility of structural damage such as cracks in the first pole piece 34a and/or the second pole piece 34c due to mutual extrusion of the core 31 can effectively improve the overall cycle performance of the battery module 10.

In one embodiment, in the direction from the end 31 a of the battery core 31 to the center of the battery core 31, the thickness of the buffer pad 40 is gradually reduced, so as to fit the first gap 32.

In one embodiment, referring to FIG. 9, the battery module 10 includes more than two battery cells 30. Each battery unit 30 includes two battery cells 31. A first gap 32 is formed between two adjacent battery cells 31 in two adjacent battery cells 30. Along the length direction X, the first gap 32 is provided through. Referring to FIG. 10, the cushion pad 40 includes a first cushion portion 41 and a second cushion portion 42. Along the thickness direction Y, one end 31a of the two end portions 31a of the cell 31 and the first buffer portion 41 are arranged mutually, and the other end 31a and the second buffer portion 42 are arranged mutually. A first buffer portion 41 and a second buffer portion 42 are respectively provided at both end portions 31a of the cell 31. The first buffer portion 41 and the second buffer portion 42 are spaced apart. The first buffer portion 41 and the second buffer portion 42 each provide support stress for the two end portions 31a of the cell 31, thereby effectively reducing the gap between the first pole piece 34a and the second pole piece 34c at the end of the cell 31 Gap at part 31a. When the cell 31 is swelled and deformed, the first buffer portion 41 and the second buffer portion 42 respectively apply a restraining stress to the two end portions 31a of the battery core 31 and act as a buffer to reduce the expansion of the end portion 31a of the battery core 31 The degree of deformation is such that the expansion degree of the end portion 31a of the cell 31 and the expansion degree of the central area of the cell 31 tend to be consistent. The surface of each of the first buffer portion 41 and the second buffer portion 42 facing the cell 31 matches the shape of the surface of the cell 31. Optionally, both the first buffer portion 41 and the second buffer portion 42 are solid structures.

In one embodiment, the wide surface of the cell 31 is arched. The surface of the first buffer portion 41 facing the battery core 31 and the surface of the second buffer portion 42 facing the battery core 31 are also arched, so as to match the shape of the wide surface. Along the length direction X, the first buffer portion 41 has an end surface facing outward and away from the second buffer portion 42, and the second buffer portion 42 has an end surface facing outward and away from the first buffer portion 41. Along the length direction X, the end surface of the first buffer portion 41 and the end surface 31b of the battery cell 31 are aligned with each other, so that the end portion 31a opposite to the first buffer portion 41 does not appear to be suspended, and the end surface of the battery cell 31 can be reduced. The portion 31a that is not covered by the first buffer portion 41 causes the possibility that the gap between the first pole piece 34a and the second pole piece 34c at the end 31a of the cell 31 cannot be reduced, and can also be reduced The portion of the end portion 31a of the battery cell 31 that is not covered by the first buffer portion 41 may cause the portion to expand too much. The end surface of the second buffer portion 42 and the end surface 31b of the cell 31 are aligned with each other, so that the end 31a opposite to the second buffer portion 42 does not appear to be suspended, which can reduce the loss of the end 31a of the cell 31. The part covered by the second buffering portion 42 causes the possibility that the gap between the first pole piece 34a and the second pole piece 34c at the end 31a of the cell 31 cannot be reduced, and can also reduce the risk of the cell 31 The portion of the end portion 31a that is not covered by the second buffer portion 42 may cause the portion to expand too much. In another example, the end surface of one of the first buffer portion 41 and the second buffer portion 42 is aligned with the end surface 31 b of the cell 31.

In one embodiment, along the length direction X, the ratio of the size of at least one of the first buffer portion 41 and the second buffer portion 42 to the length of the cell 31 is 0.06 to 0.15. Along the width direction Z of the battery cell 31, the first buffer portion 41 and the second buffer portion 42 are both equal to the width dimension of the battery cell 31. In this way, both the first buffer portion 41 and the second buffer portion 42 can effectively cover the end 31a of the battery core 31, so as to provide a good support and buffer effect on the end 31a of the battery core 31, thereby facilitating the improvement of the battery core. The balance of the buffer stress on different areas of the end 31a of 31.

Referring to FIG. 11, the abscissa in the figure represents the number of cycles of the cell 31, and the ordinate represents the capacity retention rate of the cell 31. In the case where a buffer pad of equal thickness is provided between two batteries 31 close to each other, as the number of cycles increases, the capacity retention rate shows a downward trend. In one embodiment, as shown in FIG. 10, the cushion 40 includes a first cushion 41 and a second cushion 42. From the end 31a of the cell 31 to the center of the cell 31, the thickness of the first buffer portion 41 and the second buffer portion 42 gradually decrease, and each fits the first gap 32, so that the thickness direction Y There is no gap between the upper first buffer portion 41 and the second buffer portion 42 and the battery cell 31. The first buffer portion 41 and the second buffer portion 42 are both non-equal thickness structures. In the case where the first buffer portion 41 and the second buffer portion 42 are provided between two cells 31 close to each other, as the number of cycles increases, the capacity retention rate also shows a downward trend. However, when the first buffering portion 41 and the second buffering portion 42 are arranged between two cells 31 close to each other, the rate of decrease in the capacity retention rate is less than that when a buffer pad of equal thickness is provided between two cells 31 close to each other. The rate of decrease in capacity retention. When the first buffer portion 41 and the second buffer portion 42 are arranged between two battery cells 31 that are close to each other, the overall cycle performance of the battery cells 31 can be improved.

Referring to FIG. 12, the abscissa in the figure represents the number of cycles of the cell 31, and the ordinate represents the expansion force of the cell 31. In the case where a buffer pad of equal thickness is provided between two cells 31 close to each other, as the number of cycles increases, the expansion force of each cell 31 shows an increasing trend. In one embodiment, as shown in FIG. 10, the cushion 40 includes a first cushion 41 and a second cushion 42. In the direction from the end 31 a of the battery core 31 to the center of the battery core 31, the thickness of the first buffer portion 41 and the second buffer portion 42 gradually decreases, which is adapted to the first gap 32. The first buffer portion 41 and the second buffer portion 42 are both non-equal thickness structures. In the case where the first buffer portion 41 and the second buffer portion 42 are provided between two cells 31 close to each other, as the number of cycles increases, the expansion force of each cell 31 also shows an increasing trend. However, when the first buffer portion 41 and the second buffer portion 42 are provided between two cells 31 that are close to each other, the rate of increase of the expansion force of each cell 31 is less than that between two cells 31 that are close to each other. The rising rate of the expansion force of each cell 31 when the cushion is thick. When the first buffer portion 41 and the second buffer portion 42 are arranged between two cells 31 close to each other, the cycle performance is improved, and it is better than the cycle when a buffer pad of equal thickness is set between two cells 31 close to each other performance. The arrangement of the first buffer portion 41 and the second buffer portion 42 between the two cells 31 that are close to each other can help reduce the expansion force of the cell 31 after the number of cycles reaches a predetermined value.

In an embodiment, referring to FIG. 13 or FIG. 14, the cushion 40 further includes a middle portion 43. The intermediate portion 43 is disposed between the first buffer portion 41 and the second buffer portion 42 and is in contact with the battery core 31. The dotted lines in FIGS. 13 and 14 are only used to schematically distinguish the first buffer portion 41, the middle portion 43 and the second buffer portion 42, and do not correspond to the structure of the first buffer portion 41, the middle portion 43 and the second buffer portion 42 or other parts. Form a limit. When the battery cell 31 expands during the cycle, the first buffer portion 41 and the second buffer portion 42 can support and buffer the end 31a of the battery core 31, and the middle portion 43 can support and buffer the end portion 31a of the battery core 31. The intermediate area between the end portions 31a plays a supporting and buffering role. In this way, it is possible to ensure that the forces on each area of the entire battery cell 31 are more uniform and balanced, which is beneficial to ensure that the gap between the first pole piece 34a and the second pole piece 34c at the end 31a of the battery core 31 and the first pole piece 34a and The gaps of the second pole pieces 34c in the central area of the cell 31 tend to be consistent, which is also beneficial to ensure that the expansion degree of the end 31a of the cell 31 and the expansion degree of the central area of the cell 31 tend to be the same, thereby further improving and Improve the cycle performance of the battery cell 31. The surface of the middle portion 43 facing the cell 31 matches the shape of the surface of the cell 31. Optionally, the middle part 43 is a solid structure.

The surfaces of the first buffer portion 41, the second buffer portion 42 and the intermediate portion 43 each facing the battery core 31 are attached to the surface of the battery core 31, preferably in complete contact. The first buffer portion 41, the second buffer portion 42 and the middle portion 43 are connected to each other towards the surface of the cell 31 and transition smoothly, thereby reducing the stress concentration area generated by the buffer portion on the surface of the cell 31 and causing damage to the structure of the cell 31 Possibility. Referring to FIG. 13, the first buffer portion 41, the second buffer portion 42 and the intermediate portion 43 may be split structures. Referring to FIG. 14, the first buffer portion 41, the second buffer portion 42 and the intermediate portion 43 may also be an integrated structure.

Referring to FIG. 9, a second gap 33 is formed between the battery cell 31 near the casing 20 and the casing 20 in the battery unit 30. In the direction from the end 31a of the cell 31 to the center of the cell 31, the size of the second gap 33 in the thickness direction Y gradually decreases, that is, the direction from the end 31a of the cell 31 to the center of the cell 31 , The size of the second gap 33 along the thickness direction Y is narrowed from width. A cushion 40 is provided in the second gap 33. The cushion pad 40 is in contact with the end 31 a of the battery cell 31. In an example, along the length direction X, the second gap 33 is provided through. Optionally, referring to FIG. 10, the cushion 40 includes a first cushion 41 and a second cushion 42. The first buffer portion 41 is provided between one end 31 a of the battery core 31 and the housing 20, and the second buffer portion 42 is provided between the other end 31 a of the battery core 31 and the housing 20. Both the first buffer portion 41 and the second buffer portion 42 can support the end 31a of the battery core 31, and are also used to buffer the expansion and deformation of the end 31a of the battery core 31, so as to ensure that the entire battery cell 31 close to the housing 20 is exposed to various areas. The force is more uniform and balanced, which is beneficial to further enhance and improve the cycle performance of the cell 31. Further optionally, referring to FIG. 13 or FIG. 14, the cushion pad 40 includes a first cushion portion 41, a middle portion 43 and a second cushion portion 42. The intermediate portion 43 is arranged between the first buffer portion 41 and the second buffer portion 42, which helps to ensure that the gap between the first pole piece 34a and the second pole piece 34c at the end 31a of the cell 31 and the first pole piece The gap between each of the 34a and the second pole piece 34c in the central area of the cell 31 tends to be the same, which also helps to ensure that the expansion degree of the end 31a of the cell 31 and the expansion degree of the central area of the cell 31 tend to be consistent, thereby further Enhance and improve the cycle performance of the cell 31.

In one embodiment, the battery unit 30 includes more than two battery cells 31. More than two batteries 31 are arranged in a fixed frame. In a battery unit 30, as shown in FIG. 10, FIG. 13 or FIG. 14, a rigid isolation member 50 is provided between two adjacent battery cells 31. The rigid isolation member 50 may be an aluminum plate. When the battery cell 31 in the battery unit 30 expands, the two adjacent battery cells 31 will be restrained by the rigid isolation component 50. Therefore, on the one hand, the rigid isolation component 50 and the buffer pad 40 can jointly restrain the battery cell 31. In order to effectively reduce the expansion and deformation of the battery core 31, so that the expansion degree of the end 31a of the battery core 31 and the expansion degree of the central area of the battery core 31 tend to be consistent; on the other hand, the rigid isolation member 50 can reduce the adjacent two electric The core 31 may squeeze each other due to expansion and deformation, causing structural damage to the first pole piece 34a and the second pole piece 34c. The rigid isolation component 50 can be made of a material with thermal conductivity, which can facilitate the heat dissipation of the battery core 31 through the rigid isolation component 50.

In one embodiment, the number of the first gap 32 is two. Two first gaps 32 are formed between the two end portions 31a of two adjacent cells 31, and the central regions of two adjacent cells 31 are in contact with each other so that the two first gaps 32 are not in the length direction X. Connected. A cushion 40 is provided in each first gap 32.

In one embodiment, referring to FIG. 15, each battery unit 30 includes a battery cell 31. One battery core 31 is arranged in a fixed frame. A first gap 32 is formed between two adjacent cells 31. Two adjacent battery cells 31 are provided with buffer pads 40. In an example, referring to FIG. 16, the cushion 40 includes a first cushion 41 and a second cushion 42. The first buffer portion 41 and the second buffer portion 42 are arranged at intervals along the longitudinal direction X. In another example, referring to FIG. 17, the cushion pad 40 further includes a middle portion 43. The first buffer portion 41, the middle portion 43, and the second buffer portion 42 are sequentially arranged along the length direction X and connected to each other. The first buffer portion 41, the intermediate portion 43, and the second buffer portion 42 may have a separate structure or an integrally formed structure. The dotted line in FIG. 17 is only used to schematically distinguish the first buffer portion 41, the middle portion 43 and the second buffer portion 42, and does not limit the structure of the first buffer portion 41, the middle portion 43 and the second buffer portion 42 or other components.

In one embodiment, as shown in FIGS. 18 and 19, two tabs are led out from one end surface 31 b of the battery core 31. A first gap 32 is formed between one end 31a of each of two adjacent battery cells 31, and the other end 31a of each is in contact with each other. The number of the first gap 32 is one. The first gap 32 does not penetrate in the longitudinal direction X. A cushion 40 is provided in the first gap 32. The cushion 40 is in contact with the end 31a of the cell 31

Although the present application has been described with reference to the preferred embodiments, various modifications can be made to it without departing from the scope of the present application and the components therein can be replaced with equivalents. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any manner. This application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims (10)

A battery module, which includes: Two or more battery units, the battery unit includes a battery cell, the battery cell has two ends opposite along its length, and the two or more battery cells are arranged side by side along the thickness direction of the battery cell, In two adjacent battery cells, a first gap is formed between two adjacent battery cells, and the first gap starts from one of the ends and extends along the length direction. From the end to the center of the battery core, the size of the first gap in the thickness direction gradually decreases; Cushion Wherein, the buffer pad is arranged between two adjacent battery cells, and the buffer pad is arranged in the first gap and is in contact with the end of the battery cell. The battery module according to claim 1, wherein the first gap is penetrated along the length direction, and the cushion pad includes a first cushion portion and a second cushion portion; and along the thickness direction, the One of the two ends of the battery cell is arranged with the first buffer part, and the other end is arranged with the second buffer part. The battery module according to claim 2, wherein the cushion pad further comprises an intermediate portion, the intermediate portion is provided between the first buffer portion and the second buffer portion and is in contact with the battery core . The battery module according to claim 3, wherein the first buffer portion, the second buffer portion, and the middle portion are connected to each other and smoothly transition toward the surface of the battery cell; and/or, The surface of the battery core forming the first gap is an arched surface, and the surfaces of the first buffer portion, the second buffer portion and the intermediate portion each facing the battery core are attached to the battery core Together. The battery module according to claim 3, wherein the first buffer part, the second buffer part and the intermediate part are an integral structure. The battery module according to claim 2, wherein along the length direction, the end surface of the first buffer portion is aligned with the end surface of the battery cell, and/or, along the length direction, the first The end faces of the two buffer parts are aligned with the end faces of the battery core. The battery module according to claim 2, wherein, along the length direction, the ratio of the size of the first buffer portion to the size of the battery cell is 0.06 to 0.15, and/or the second buffer The ratio of the size of the part to the size of the battery is 0.06 to 0.15; Alternatively, along the width direction of the battery core, the buffer pad and the battery core have the same size. The battery module according to claim 1, wherein the battery cell includes an electrode assembly and a packaging bag, the electrode assembly is disposed in the packaging bag, and the electrode assembly includes first pole pieces with opposite polarities and For the second pole piece, the thickness of the first pole piece and the second pole piece gradually increase from the end to the center of the cell. The battery module according to claim 1, wherein: The battery module further includes a casing, the battery unit is disposed in the casing, and a second gap is formed between the battery cell near the casing and the casing. In the direction from the center of the battery cell to the center of the battery, the size of the second gap along the thickness direction gradually decreases, and the cushion pad is provided in the second gap, and the cushion pad and the battery core The end contact. 8. The battery module according to any one of claims 1 to 8, wherein the battery unit includes more than two battery cells, and a rigid isolation member is arranged between two adjacent battery cells.

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